1. Field of the Invention
The present invention relates to a substrate for an electrophotography photosensitive body and an electrophotography photosensitive body that uses an electrophotography process with at least one contact charging method as a charging mechanism (henceforth referred to a contact charging process). The present invention also relates to an electrophotography device equipped with this photosensitive body.
2. Description of the Related Art
Traditionally, the technology for electrophotography had developed in the field of the copier machine.
Recently, it has also been applied to laser printers and the like, and compared to the prior impact printers, these laser printers are much improved in terms of image quality, speed, and quietness. The electrophotography photosensitive body mounted onto these devices is formed by providing a photoconductive layer on a surface of a conductive cylindrical substrate.
Photoconductive organic materials are typically included in the materials for this photoconductive layer. In general, its layer structure is a function-separated structure (layered type). This layered type is commonly a negative charging type photosensitive body in which an undercoat layer (UCL), a charge generating layer (CGL), and a charge transport layer (CTL) are laminated in that order on top of an aluminum substrate.
For the undercoat layer, a layer that is primarily of a polyamide resin is commonly used. However, although this undercoat layer is inexpensive, there are many problems in terms of environmental resistance. In particular, there can be significant fluctuations in its properties due to humidity. As a way to combat this problem, instead of the polyamide resin film described above, an anodic oxidation film that is formed by anodic oxidation treatment of an aluminum substrate is used as the undercoat layer. In particular, in high temperature and high humidity environments, the anodic oxidation film is thought to have better reliability.
In the related art, a corona charging method is often used for the charging mechanism in the electrophotographic process. However, recently, for the purposes of improving charging efficiency and miniaturizing the device and reducing ozone amounts and the like, devices that use a contact charging method have been increasing.
The contact charging method conducts charging by direct contact of the charging member with the photosensitive body surface. However, with the contact charging method, any small irregularities on the substrate surface can easily result in damage to the insulation of the photosensitive layer.
In addition to contact charging devices used in charging processes in the electrophotography process, the contact charging devices described here also include devices that charge by contact with the electrophotography photosensitive body such as contact transfer devices used in a transfer process and the like.
With contact transfer, because paper and the like are normally present between the photosensitive body and the contact transfer device, insulation damage does not readily occur. However, with cut paper, direct contact between the photosensitive body and the contact transfer device cannot be avoided between one page and the next. As a result, damage to insulation is similarly a problem.
In particular, when OHP sheets are used, because the transfer voltage becomes high, insulation damage occurs readily. Stated more concretely, when small defects in the material on the substrate surface or small splinters from cutting the substrate surface are present, the electric field becomes concentrated in that area when voltage is applied, and damage to the insulation occurs.
When damage to the insulation occurs, in reverse developing systems, this results in black spots on white parts, and in normal developing, this becomes white spots in black parts. When these spots are numerous, they can prove to be a serious printing obstacle. In particular, in the case of reverse developing, even small black dots appear readily, and this becomes a frequent problem.
Various improvements have been proposed for this problem arising from insulation damage. For example, Japanese Patent Number 2661418, discloses a method for anodic oxidation of the surface of the aluminum substrate used for the photosensitive body.
Unfortunately, after a detailed examination by the present inventors, by using this method alone, only the problem of comparatively large printing defects of diameter 0.5 mm or greater was sightly minimized, and the practical problem of minute printing defects (diameter of approximately 0.1-0.5 mm) due to leakage (insulation damage) during charging was not sufficiently resolved. Consequently, this disclosure has not proved successful in solving the problems noted above.
It is an object of the present invention to overcome the concerns raised and discussed above.
It is another object of the present invention is to provide an electrophotography photosensitive body substrate and an electrophotography photosensitive body in which an electrophotography photosensitive body, wherein the body includes a substrate having a sealed aluminum anodic oxidation film on its surface and a photosensitive layer on top of this substrate surface, and used in a contact charging process, and thereby prevent the creation of small insulation damage of around diameter 0.1-0.5 mm.
It is another object is to provide an electrophotography device using this photosensitive body.
It is another object of the present invention is to provide the above substrate, electrophotography photosensitive body, and electrophotography device that are used in a contact charging system of a reverse developing system.
According to one embodiment of the present invention, the above object is achieved by an electrophotography photosensitive body substrate having an aluminum anodic oxidation film on its surface and being used in a contact charging process, wherein: the anodic oxidation film is a film that is sealed by a sealing agent in which an anion surface active agent is added.
According to another embodiment of the present invention, there is provided an electrophotography photosensitive body substrate, wherein: the sealed aluminum anodic oxidation film is a film that is sealed by a sealing agent in which an anion surface active agent is added in an amount necessary for preventing the formation of sealing deposits.
According to another embodiment of the present invention, there is provided an electrophotography photosensitive body substrate as described in any embodiment supported, wherein: a phosphoric ester surface active agent is used as the anion surface active agent.
According to another embodiment of the present invention, there is provided an electrophotography photosensitive body substrate as described in any embodiment above or below, wherein: the phosphoric ester surface active agent has a concentration of 0.1-2.0 g/l with respect to water.
According to another embodiment of the present invention, there is provided an electrophotography photosensitive body substrate as described in any embodiment above or below, wherein: a formaldehyde condensate of naphthalene sulfonate is used as the anion surface active agent.
According to another embodiment of the present invention, there is provided an electrophotography photosensitive body substrate as described any embodiment above, wherein: the formaldehyde condensate of naphthalene sulfonate has a concentration of 0.1-3.0 g/l with respect to water.
According to another embodiment of the present invention, there is provided an electrophotography photosensitive body substrate as described any embodiment provided herein, wherein: a formaldehyde condensate of bisphenol A sulfonate is used as the anion surface active agent.
According to another embodiment of the present invention, there is provided an electrophotography photosensitive body substrate as described in each embodiment discussed, wherein: the formaldehyde condensate of bisphenol A sulfonate has a concentration of 0.2-5.0 g/l with respect to water.
According to another embodiment of the present invention, there is provided an electrophotography photosensitive body substrate as described in any embodiment above, wherein: nickel acetate is added to the sealing agent.
According to another embodiment of the present invention, the objects discussed above are provided by an electrophotography photosensitive body that uses an electrophotography photosensitive body substrate as described any embodiment discussed above or below.
According to another embodiment of the present invention, the above objects may be achieved by an electrophotography device, comprising: an embodiment of an electrophotography photosensitive body described above, and an embodiment of a contact charging device.
According to another embodiment of the present invention, it is preferable to have an electrophotography device of any embodiment described which is a reverse development system.
Although the detailed mechanism for the present invention is not known, in the sealing treatment of the aluminum anodic oxidation film, the anion surface active agent of a specified concentration contained in the sealing agent adjusts the uniformity of the sealing of the film surface and inhibits the formation of surface sealing deposits which can cause insulation damage by concentrating the electric field.
Stated more concretely, the surface active agent described above dissolves out from the aluminum anodic oxidation film and is adsorbed onto the surface of hydrated aluminum that is dissolved in the sealing solution, or it is adsorbed onto the aluminum anodic oxidation film surface.
As a consequence, the aggregation of particles of hydrated aluminum, or their deposition onto the anodic oxidation film surface is prevented, and as a result, the creation of sealing deposits becomes difficult.
With nickel acetate sealing in which nickel acetate is further added to the sealing agent, by the surface active agent of the present invention, the accumulation of hydrolyzed nickel hydroxide onto the sealing surface is similarly and beneficially prevented.
In simple terms, the surface active agent of the present invention is a compound with a hydrophilic portion and a lipophilic portion both in one molecule.
With regard to the properties of the surface active agent in a solution or a dispersion solution, it is adsorbed and oriented at the solvent and solute or dispersoid interface, and it has the action of lowering the interfacial tension.
According to the ionic property shown when there is partial dissociation of the lipophilic portion, they are largely divided into anionic, cationic, amphoteric, non-ionic surface active agents and the like.
Anionic surface active agents of the present invention include carboxylates, sulfonates, sulfate esters, phosphoric esters, polymerized polymers, and polycondensation polymers, and the like.
In the present invention, all of the classes described above are effective as anionic surface active agents, but phosphoric ester surface active agent and naphthalene sulfonate formaldehyde condensate, which is a polycondensation polymer, are especially well suited.
Phosphoric ester surface active agents are Phosphanol RS610 manufactured by Toho Kagaku Kogyo Corp. Ltd., Adecacole PS, CS, TS, manufactured by Asahi Denka Kogyo Corp. Ltd., Electrostripper N, K manufactured by Kao Corp. Ltd.
Formaldehyde condensates of naphthalene sulfonate are Demol N, RN, NL, RN-L, T manufactured by Kao Corp. Ltd.; Ionet D-2 manufactured by Sanyo Kasei Kogyo Corp. Ltd., and Lunox 1000 manufactured by Toho Kagaku Kogyo Corp. Ltd.
Formaldehyde condensates of bisphenol A sulfonates include AMN-1 manufactured by Senca Corp. Ltd.
The amount of these surface active agents added to the sealing agent has a close relationship with the formation of sealing deposits. The amount needed in the present invention is different and particular for each surface active agent. This is determined by whether the formation of sealing deposits that causes insulation damage leading to image defects is prevented.
Preferably, the amount of the anionic surface active agent added to the sealing agent is in the range of 0.01-10 g/l with respect to pure water.
In Japanese Laid-Open Patent Publication Number 10-333342, there is a description of including a surface active agent in the rinsing solution after sealing treatment. Unfortunately, in this case, the rinsing solution that has the surface active agent is not used for dissolving and eliminating deposits during sealing as described above. Therefore, the technical idea of the two is completely different.
In Japanese Laid Open Patent Number 11-84705, paragraph 0023, states xe2x80x9cIn the sealing treatment process of both high temperature sealing treatment and low temperature sealing treatment, a surface active agent can be included in the treatment solution for the purposes of improving the wettability of the treatment solution, or a surface active agent is not included.xe2x80x9d However, later, there is also stated that xe2x80x9cpreferably, a surface active agent is not included.xe2x80x9d Consequently, in the embodiments described afterwards, a surface active agent is not included in the sealing solution. Thus this brief comment is supportably excludable.
In Japanese Patent Number 2661418, it states that a surface active agent can be added to a sealing solution of nickel fluoride or nickel acetate. However in the embodiments to be described, there are no concrete examples in which surface active agents are added.
In Japanese Laid Open Patent Number 11-38662, the same inventors as the present invention achieved a specified admittance value by adding a specified anionic surface active agent to the sealing solution. The growth of the film in the vertical direction is suppressed, and a photosensitive body having a highly sealed surface that is uniform and smooth with a high wettability is provided. As the specified anionic surface active agent only, phosphoric esters, formaldehyde condensate of naphthalene sulfonate, formaldehyde condensate of bisphenol A sulfonate are disclosed or supported.
As will be noted below, there is no disclosure, or even any indication of the present invention, which relates to the relationship between the optimal addition amount (concentration) for these specified anionic surface active agents in the sealing solution and the insulation damage that is readily generated when a photosensitive body, that uses a photosensitive substrate equipped with an aluminum anodic oxidation film that has been sealed, is used in an electrophotography device with a contact charging process.
The above, and other objects, features, and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.